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Eni applies for Oliktok Point jetty, dredging Dredging for arrival of barges with modules for Nikaitchuq project; jetty for protection for launching, recovery of small boats Kristen Nelson Petroleum News
Eni is applying to dredge at Oliktok Point to allow arrival of large modules on barges this summer, and is also applying to construct a jetty for local subsistence users.
Eni is building a production pad for its Nikaitchuq development at Oliktok Point adjacent to ConocoPhillips Alaska’s seawater treatment plant, work which will be completed this year.
Local access has been provided by maintaining a gravel ramp where small skiffs could be tied up and launched, but marine traffic has increased in recent years, Eni said in its plan of operations for the marine jetty at Oliktok, and now includes operations by Eni, Pioneer, ConocoPhillips and their contractors. In 2009 a temporary floating dock was deployed to support geophysical operations.
The jetty would be on the west side of Oliktok Point where it would be sheltered from waves and ice impacts generated by prevailing northeast winds.
Sandbag construction The jetty would be constructed of 4-cubic-yard sandbags with material stockpiled at the facility and would cover about half an acre of seafloor; it would be some 250 feet long by 80 feet wide by 8 feet high.
The corps said the sheltered area is intended for subsistence users, spill response teams and industry operators.
Construction would be done in the late winter of 2010 when water depths up to four feet are frozen to the seafloor.
Sea ice would be removed from the construction area with dozers and excavators, Eni said in its plan, sandbags would be filled with soil from a stockpile in place at the Oliktok production pad and the bags would be individually placed on the seafloor.
Eni said some maintenance dredging might be required to maintain water depths at the boat landing at about four to five feet below the mean sea level. Dredged materials would be used to fill replacement sandbags or discharged in an area seaward of the jetty.
Navigational dredging The navigational dredging is to support delivery of major oil production modules for Nikaitchuq on large barges, approximately 105 feet wide by 400 feet long and with a draft of 7 feet when loaded.
Eni said the major modules for the Nikaitchuq development will be transported from construction yards in the Gulf of Mexico to the Oliktok Point dock this summer using two or more barges owned and operated by Crowley Maritime Services Inc.
The barges will be hauled to the general area using deepwater tugs and then hauled to the dock face by shallower draft tugs.
To safely offload the barges they will need to be grounded at the dock face so loads can be moved off using large wheeled transport devices and the grounding area will need to be relatively flat.
The barge preparation work could be done with either a crane-operated dredge or by screeding. Screeding is less intrusive than dredging. Eni said it involves scraping sediments from one area of the dock face to a deeper area near the dock; the sediments are not removed from the water and will not leave the general docking area.
Screeding involves moving sediments with a plow attached to another barge, with the plow controlled vertically using hydraulics. Current plans call for screeding an area of roughly 500 feet by 500 feet at the dock face to a uniform depth of 7 to 7.5 feet, depending on the final barge load.
Estimates are that screeding will move some 2,000 to 3,000 cubic yards of seafloor sediments from the immediate area of the dock face to relatively deeper water in the center and north side of the screeding area.
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